How do buses work?

The short answer

Two names: Supratours and CTM.

Two names: Supratours (run by ONCF, departs from train stations) and CTM (independent, broader network). Both are modern and air-conditioned. Marrakech to Essaouira: about 3 hours, 80–100 MAD. Popular routes sell out on weekends — especially Marrakech–Essaouira and Fes–Chefchaouen.